wondering what people's thoughts are on the following..........as the back garden opposite mine has an old wisteria, must be at least 30 years old given the thickness of the trunk and although it provides a great backdrop neither of the neighbours whose gardens it grows across worry about pruning it, well not properly anyway other than one of them hacking some of stems that got in the way of his gate back in july.

as they don't live on my street i don't know either of them other than a quick hello and i was thinking of introducing myself in august and offering to prune it properly for them to maximise flowering. admittly they might think i'm a little strange, but us gardeners can be........

anyway i never plucked the courage up to ask them, but i'm thinking of writing them a xmas card and offering to prune it in January to maximise flowering, and my question is twofold. firstly do u think a letter is best or should i just knock on their door, and secondly does it matter that the wisteria was not given its august prune as i'm guessing you can still prune each stem back to 2/3 buds in january and this will encourage more flowers. fyi its the wisteria variety that's purple and flowers follow the first leaves

thanks for your help